A worker at a research laboratory in Siberia died. Local reports say she may have broken a test tube of pneumonic plague bacteria. Russia said the woman's death was from "pneumonia of an unknown origin" and not plague. The USA said there was no "cause for alarm," but officials should "keep an eye on it".

Pneumonic plague can be deadly. It can kill in 18 hours. It spreads quickly through the air when someone coughs. It can be treated if drugs are given when symptoms appear. A scientist said: "Pneumonic plague can spread from person to person, and that is why there is the concern around this."